Interpretive Summary: Oleic acid is a compound that is found in the fats of plants and animals. The compound is not toxic to humans, but it can kill some bacteria that cause food spoilage and human diseases. In this experiment, the ability of oleic acid to kill bacteria found on poultry skin was examined. Skin from commercial broilers was washed once or twice in solutions of oleic acid. The washed skin was rinsed with water, and bacteria in the rinsate were enumerated. Fewer bacteria were recovered from rinsates of skin washed in oleic acid than from skin that was not washed in oleic acid. Additionally, fewer bacteria were recovered from rinsates of skin samples washed in high concentrations of oleic acid than from skin washed in low concentrations of oleic acid. There was no difference in the number of bacteria recovered from rinsates of skin washed once or twice in oleic acid. Washing poultry skin in solutions of oleic acid also reduced the number of bacteria that remained attached to poultry skin. Some of the bacteria isolated from poultry skin were quickly killed by oleic acid while other bacteria were more resistant to oleic acid. Findings indicate that washing processed poultry carcasses with solutions of oleic acid may be considered as a treatment for reducing the number of undesirable bacteria on the carcasses.

Technical Abstract:
The effect of oleic acid on the native bacterial flora of poultry skin was examined. Skin from commercial broiler carcasses was washed once or twice in solutions of 0, 2, 4, 6, 8, or 10 per cent (wt/vol) oleic acid and rinsed in peptone water. Total aerobes, Enterobacteriaceae, campylobacter, and enterococci in the rinsates were enumerated. Significantly fewer total aerobes, Enterobacteriaceae, campylobacter, and enterococci were recovered from rinsates of skin washed in oleic acid than from control samples. Additionally, fewer bacteria were generally recovered from rinsates of skin washed in higher concentrations of oleic acid than from skin washed in lower concentrations of the fatty acid. In most cases, there was no significant difference in the number of bacteria recovered from rinsates of skin washed once or twice in the same concentration of oleic acid. Washing skin samples twice in 10 per cent solutions of oleic acid also significantly reduced the number of total aerobes, Enterobacteriaceae, campylobacter, and enterococci that remained attached to the skin. In vitro, isolates of Campylobacter sp., Enterococcus faecalis, and Listeria monocytogenes possessed the least resistance to the antibacterial activity of oleic acid, while Escherichia coli and Pseudomonas aeruginosa showed higher resistance. Enterobacter cloacae, Staphylococcus lentus, and Salmonella typhimurium exhibited the greatest resistance to the antibacterial activity of oleic acid. Findings indicate that oleic acid may be used to reduce the number of spoilage and pathogenic bacteria on the skin of processed poultry carcasses.